I did `mdadm --add /dev/md1 /dev/sdd2` and got the following in my kernel log: Mar 25 23:56:21 beast kernel: md: bind<sdd2> Mar 25 23:56:21 beast kernel: RAID5 conf printout: Mar 25 23:56:21 beast kernel: --- rd:3 wd:2 fd:1 Mar 25 23:56:21 beast kernel: disk 0, o:1, dev:sda2 Mar 25 23:56:21 beast kernel: disk 1, o:1, dev:sdb2 Mar 25 23:56:21 beast kernel: disk 2, o:1, dev:sdd2 Mar 25 23:56:21 beast kernel: md: syncing RAID array md1 Mar 25 23:56:21 beast kernel: md: minimum _guaranteed_ ...

In my case, I want to emphasize the following: my WD Green drives are strictly a data store. The system runs from a compact flash card. Though I disabled them anyway, many daemons, such as syslog, sshd, cron, fetchmail, etc, should only affect the *system* drive. However, daemons like nfs and smbd can obviously affect the data store. Even so, I wouldn't expect them to cause a disk access unless a request is made. The point is, in my opinion, a non-system partition should be that much ...

Hello, The 4096-byte sector drives work fine with mdadm. The main problem you are going to run into with the WDC Green drives is their 8 second "idle" setting. After 8 seconds, by default, the drive parks its heads. This can lead to an amazingly high Load Cycle Count (LLC) after just a month of operation due to the fact that most disk access happens around that time causing the drive to park and unpark in repeated cycles. To fix this, find a utility called wdidle3 (I have it, if you are ...

The feature will be added in version 5.40. Or get if from SVN --

I originally noticed the problem after having the drives for 4 weeks. They LCC was at around 27,000 on each drive until I changed the timeout on the drives to 300 seconds. -Peter --

For what it's worth... that head parking feature actually saves a measurable amount of power. On my system, with four drives, there is about a 10 watt (AC) difference between all four heads parked and all four heads non-parked. This finding is consistent with the This will prevent the rapidly increasing Load Cycle Count SMART counter. However, in my opinion, it also removes a useful power-saving feature of these drives. In other words, my system is mostly idle; I want the heads to be ...

I must also note, that I was seeing the drives stop and start even when there *was* activity on the disks. -Peter --

Thanks. I don't know if that's high or low. To me it's just a number. Following along from Matt Garman's reply I went back and looked at when I built this machine for my dad. (How many here have 85 year old fathers who have run Linux for 7 years instead of windows? Give him a cheer!) ;-) I agree with Matt about trying to save power. This machine is 40 days old today, at least counting since he first booted it at home. It's been up and running since then. 40 Days is 3,456,000 ...

On Thu, Mar 25, 2010 at 7:09 AM, Anshuman Aggarwal Please, read the wikipedia page first, http://en.wikipedia.org/wiki/RAID and then this http://wiki.tldp.org/LVM-on-RAID (some links need updating, but it's still up to date for concepts) With that background nearly out of the way, please stop, and read them both again. Yes, seriously. In order to prevent data loss you'll need to have a good understanding of what RAID does, so that you can watch out for ways it can fail. The ...

Thanks again. I have visited those pages (twice no less) and nothing seems to be new from the concepts (both raid and lvm) since I last studied them. My problem is that I'm not familiar enough with the recovery tools and the common practical pitfalls to do this comfortably without the hand holding of this mailing list :) Here is the requested output: Note: Since I have 3-4 other arrays running (root device etc.) which don't have anything to do with this one and are all working fine...I am just ...

Why not treat this similar to how hardware RAID manages disks & spares? Disk has no metadata -> new -> use as spare. Disk has metadata -> array exists -> add to array. Disk has metadata -> array doesn't exist (disk came from another system) -> sit idle & wait for an admin to do the work. As to identify disks and know which disks were removed and put back to an array, there's the metadata & there's the disk's serial number which can obtained using hdparm. I also think that all disks now include ...

I do that too (multiple arrays using partitions). My reason for that is to make future upgrades less painful as it is possible to just copy and drop one array at a time. --